#include<iostream>

using namespace std;
#include<vector>
#include<algorithm>
class Solution {
public:
    int triangleNumber(vector<int>& nums) {
        int n = nums.size(), left = 0, right = n - 1, count = 0;
        sort(nums.begin(), nums.end());
        for (int i = n - 1; i >= 2; i--)
        {
            int left = 0; right = i - 1;
            while (left < right)
            {
                if (nums[left] + nums[right] > nums[i])
                {
                    count += right - left;
                    right--;
                }
                else
                {
                    left++;
                }
            }

        }

        return count;

    }
};
int main()
{
	return 0;
}